Molecular taxonomic identification and species-level phylogeny of the narrow-mouthed frogs of the genus Rhombophryne (Anura: Microhylidae: Cophylinae) from Madagascar

Abstract

The study of diamond frogs (genus Rhombophryne, endemic to Madagascar) has been historically hampered by the paucity of available specimens, because of their low detectability in the field. Over the last 10 years, 13 new taxa have been described, and 20 named species are currently recognized. Nevertheless, undescribed diversity within the genus is probably large, calling for a revision of the taxonomic identification of published records and an update of the known distribution of each lineage. Here we generate DNA sequences of the mitochondrial 16S rRNA gene of all specimens available to us, revise the genetic data from public databases, and report all deeply divergent mitochondrial lineages of Rhombophryne identifiable from these data. We also generate a multi-locus dataset (including five mitochondrial and eight nuclear markers; 9844 bp) to infer a species-level phylogenetic hypothesis for the diversification of this genus and revise the distribution of each lineage. We recognize a total of 10 candidate species, two of which are identified here for the first time. The genus Rhombophryne is here proposed to be divided into six main species groups, and phylogenetic relationships among some of them are not fully resolved. These frogs are primarily distributed in northern Madagascar, and most species are known from only few localities. A previous record of this genus from the Tsingy de Bemaraha (western Madagascar) is interpreted as probably due to a mislabelling and should not be considered further unless confirmed by new data. By generating this phylogenetic hypothesis and providing an updated distribution of each lineage, our findings will facilitate future species descriptions, pave the way for evolutionary studies, and provide valuable information for the urgent conservation of diamond frogs.

Keywords:

• amphibians
• candidate species
• diamond frogs
• mitochondrial lineages
• northern Madagascar
• species-identification
• systematics

Acknowledgements

We are grateful to numerous colleagues, students, and guides for their collaboration over many years. This work was carried out in the framework of collaboration accords among the authors’ institutions, the Mention Zoologie et Biodiversité Animale (Former Department of Animal Biology) of the University of Antananarivo, the Parc Botanique et Zoologique de Tsimbazaza, and the Ministry of the Environment and of the Sustainable Development of the Republic of Madagascar. We thank the Ministry of the Environment and Sustainable Development for issuing research and export permits over the last three decades. We thank C. Drehlich for permission to use some sequences that have been generated by her. Finally, we would like to thank the editor and the reviewers for their comments on our contribution.

Disclosure statement

The authors have no conflict of interest to declare.

Supplemental material

Supplemental material for this article can be accessed here: http://dx.doi.org/10.1080/14772000.2022.2039320.

Associate Editor: Dr David Gower

Additional information

Funding

Financial support to various field campaigns was provided by the Saint Louis Zoo’s Field Research for Conservation program of the Wildcare Institute [FRC# 12-12], [FRC# 16-09]. This work was also funded by Portuguese National Funds from FCT (Fundação para a Ciência e a Tecnologia) through the Exploratory Research Project [IF/00209/2014/CP1256/CT0011] awarded to AC, the contract to AC [2020.00823.CEECIND/CP1601/CT0003], the doctoral fellowship to FB [PD/BD/128493/2017], the doctoral fellowship to BS [PB/BD/106055/2015], and the post-doctoral fellowship of AJMP [SFRH/BPD/111015/2015]. It was also funded by a DFG (Deutsche Forschungsgemeinschaft; German Research Foundation) grant to MDS [SCHE 2181/1-1]. AA was financially supported by the Swedish Research Council [2019-05191], the Swedish Foundation for Strategic Research [FFL15-0196], and the Royal Botanic Gardens, Kew.